LX 2931 (LX 3305) is an inhibitor of sphingosine 1-phosphate (S1P) lyase. S1P lyase is an enzyme identified as a promising new target on a pathway associated with regulation of the immune system. Lexicon Pharmaceuticals, Inc. was developing LX 2931 for the treatment of rheumatoid arthritis. LX 2931 has disappeared from the pipeline of Lexicon Pharmaceuticals, Inc. In preclinical studies LX 2931 was effective against experimental cerebral malaria, lung inflammation in a F508del CFTR murine cystic fibrosis model and osteoporosis.

LFF-571 is a novel semisynthetic thiopeptide antibiotic with potent activity against a variety of Gram-positive pathogens, including Clostridium difficile. LFF-571 was generally safe and well tolerated in single and multiple oral doses in healthy subjects. There were no deaths, no serious adverse events, and no subject withdrawals due to an adverse event. The most common adverse event was diarrhea, gastrointestinal pain or distension was also noted. Similar to healthy volunteers, patients with C. difficile infections exhibited high fecal concentrations and low serum levels of LFF571. Novartis is developing oral LFF 571 for the treatment of Clostridium difficile infections. LFF 571 binds to bacterial elongation factor Tu (EF-Tu) in domain 2. Phase-II development is ongoing in USA and Canada.

N(ω)-hydroxy-nor-L-arginine (nor-NOHA), an arginase inhibitor, has therapeutic potential in the treatment of cardiovascular and obstructive airway diseases. Nor-NOHA is a reversible, competitive arginase inhibitor. The affinity of nor-NOHA for the to the arginase active site was found in the nanomolar range. Nor-NOHA has proven to be one of the strongest arginase inhibitors. Inhibition by nor-NOHA is ten times more potent on arginase II than on arginase I. The pharmacokinetics of nor-NOHA is characterized by high bioavailability, close to 100% after multiple dose and rapid elimination resulting in t1/2 of 15–30 min after intravenous and intraperitoneal administration to rats. Arginase inhibition with Nor-NOHA increased circulating arginine levels and decreased hepatic damage during liver I/R injury. Arginase blockade represents a potentially novel strategy to combat hepatic I/R injury associated with liver transplantation. Nor-NOHA is under investigation in clinical trial NCT02009527 (Arginase inhibition in ischemia-reperfusion injury).